Entosthodon Schwägrichen, 1823.

Entosthodon, like other members of the Funariales, is strongly reminiscent of some members of the Bryaceae. This resemblance is shown by the common possession of large and thin-walled cells, the tendency of many species to have a somewhat developed limbidium, and the basically comose growth pattern also exhibited by some members of the Bryaceae. Despite this basic resemblance, the two families are classified into different orders on strong phylogenetic and morphologic bases. Perhaps the most diagnostic of features of the Funariales is the endostome position. All other groups of doubly peristomate mosses except the Funariales have the endostome insertion alternate with the exostome insertion. Thus, a view of the outer surface of the peristome of a Bryalean moss under the compound microscope will show the endostome segments peeking out from between the peristome teeth. It is difficult to see the endostome in a similar view of the peristome of a Funarialean moss because each endostome segment will be positioned precisely behind each exostome tooth. Another unusual feature of most Funariales is the nature of the stomates in the capsule walls. Typical stomates are formed by a longitudinal division of the guard cell primordium to make two kidney-bean shaped guard cells that define an opening between them. In most Funariales, the last division is incomplete such that the opening is defined but the guard cells are not completely separate, and thus they together form a single doughnut-shaped cell. There are subtle gametophytic differences between the Funariales and Bryales in gametophytic features. The cells of both are large and thin-walled but the basic form of the Funariales median laminal cell is rectangular while that of the Bryales is elongate-hexagonal. The rhizoids of most Bryales are papillose; those of most Funariales are smooth.

Key to Entosthodon

Among the Funariales, Entosthodon is the genus with exserted, erect and symmetric capsules with the endostome reduced and the exostome present. It is in general smaller than either Funaria or Physcomitrium but there is much overlap in size between the genera.

B. Peristome double; leaves ovate to elliptic ovate; suboral exothecial cells long and narrow, to 6 times as wide as long in up to 8 rows .....Entosthodon californicusB. Exostome present and well-developed, to 250 µm long, endostome absent; leaves ligulate; suboral exothecial cells short rectangular, to 3 times as wide as long in only a few rows .....Entosthodon kochii

C. Costa broad and long, ending at least in the base of the acumen; capsules pyriform, less than 2:1 .....Entosthodon drummondiiC. Costa not so extended .....D

E. Exostome long and well-developed with teeth of newly deoperculate capsule meeting at their tips in the open capsule mouth; capsules pyriform, more than twice as long as wide; spores 28-30 µm in diameter; endostome present .....Entosthodon bolanderiE. Exostome abortive, consisting of only a few cell fragments; capsules short pyriform to oblong, less than twice as long as wide; spores 35-40 µm in diameter; endostome absent .....Entosthodon tucsoni

F. Leaves nearly entire or finely crenulate, bordered by several rows of narrower cells .....Entosthodon attenuatusF. Leaves with at least some serrulations near the apex, elimbate .....G

G. Capsules somewhat inclined and asymmetric; terminal cells in leaf acumen markedly elongated with only one or 2 tiers of cells in that acumen; suboral cells of exothecium not or hardly differentiated .....Entosthodon rubrisetusG. Capsules strictly erect and symmetric; terminal cells of acumen not so elongate; suboral cells differentiated in 2-4 rows, transversely elongated .....H